The adult-comedy -- which features Diaz, 38, as a drugged-up, uninterested seventh grade substitute teacher -- has been deemed everything from "breezily crude" to "refreshingly raucous."

"There is no chemistry, or indeed even mutual awareness between Diaz and Timberlake," Roger Ebert says of the former real-life couple. "You know those annual Bad Sex Awards for the worst sex scene in a movie? Their dry-humping scene deserves an award for the decade. The scene itself is pathetic. The shot it ends on -- the wet spot on Timberlake's blue jeans -- had the preview audience recoiling."

But New York Times writer Manohla Dargis calls the film "a breezily crude comedy about unladylike pleasures like guzzling booze, swearing at children and being mean because, well, you can be ... Cameron Diaz taps into her inner thug."

Bill Goodykoontz of the Arizona Republic credits actor Jason Segal, who plays a cynical gym teacher, as the film's only character who "seems like a real person instead of a caricature."

MSN Movies' Glenn Kenny, however, calls "Bad Teacher" "a refreshingly raucous comedy that comes surprisingly close to completely living up to its lack of conviction."